One-pion exchange model in high energy nucleon-nucleon collisions

The one pion exchange model is applied to the investigation of inelastic proton-nucleon interactions with a primary kinetic energy of 8·3 GeV. The experimental comparison is carried out using a modified momentum-energy four-vector of the virtual pion, , which is determined from the energy and angle of emission of the recoil nucleon. It is shown that the OPE model — if we include the pion-nucleon resonance (T=3/2) effects — may describe the basic mechanism of peripheral interactions for <0·2 (3)².

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() 8,3 GeV. 4- - . . , - (T=3/2), <0,2 (3)².

     

The Split of the Dirac Hamiltonian into Precisely Predictable Energy Components

We are dealing with the Dirac Hamiltonian H = H₀ + V with no magnetic field and radially symmetric electrostatic potential V = V(r), preferably the Coulomb potential. While the observable H is precisely predictable, its components H₀ (relativistic mass) and V (potential energy) are not. However they both possess precisely predictable approximations H₀ and V which approximate accurately if the particle is not near its nucleus. On the other hand, near 0, H₀ and V are practically unpredictable, perhaps in agreement with the fact, that a neutrino also should be in the game. [We have not yet studied the corresponding observables for the ( 12-dimensional) problem of electro-weak interaction.] Mathematically we are focusing on the spectral theory of the unbounded self-adjoint operators H₀ and V . We can prove that V is unitarily equivalent to V(r) again, by a unitary map given as Wiener-Hopf-type singular integral operator in the standard separation of variables for radially symmetric Dirac Hamiltonians. [This is, as far as the continuous spectrum is concerned.] Very similar unitary equivalence holds for H ₀ and H ₀. We are tempted to regard this as a form of renormalization.     

Self interstitial trapping at Hf impurities in Niobium

After electron irradiation at 15 K of Niobium doped with¹⁸¹Hf the trapping of defects at the Hf impurities was observed by means of the perturbed angular correlation method. The results are interpreted as the formation of Hf-Nb mixed dumbbells which are formed at 5 K and are stable up to 80 K.     

A new method for complex spectral measurement in millimeter and submillimeter wave range

New method for measuring complex transmission or reflection coefficients has been proposed and demonstrated using a simple setup. High measurement quality was achieved: phase sensitivity 0.005 rad., amplitude reproduceability 1%, dynamic range to 10⁷ ÷ 10⁸ (previously 10⁴), phase shift range to be measured 10⁵. It is effective for BWT-Spectroscopy due to the absence of any mechanical adjustments during electronic frequency scan.     

Electronic Structure of Nanostructured Nickel Oxide Using Ni 2p XPS Analysis

We examine the electronic structure of nanostructured nickel oxide with an average particle size of 4–5nm using Ni 2p X-ray photoelectron spectrum. The most striking features of the spectrum are the Ni 2p main line broadening and an increase in the relative intensity of the 1.5eV satellite. We explain the observations as due to an enhancement in the non-local screening process on the basis of Ni₇O₃₆ cluster model by taking into account the large surface area to volume ratio and high Ni²⁺ vacancy concentration in nanostructured nickel oxide. The important contribution of an enhanced Ni 3d–O 2p hybridization and the origin of shake-up peaks above the 7eV satellite is also discussed. The study underlines the importance of factors such as the actual local environment of the core hole site, defect density and distribution, possible structural transitions, etc. in determining the Ni 2p core level X-ray photoelectron spectrum of nanostructured nickel oxide and shows that the actual synthesis routes and the thermal history greatly influence the electronic structure of nanostructured nickel oxide.     

Studies of recombination X-ray-laser gain and gain-medium uniformity

The time evolution of the uniformity of the line-shaped X-ray-laser gain medium and the spatial characteristics of the recombination X-ray-laser gains of the Li-like ions are studied using long (900 ps) and short (100 ps) laser pulses.     

Der Einfluss von Beimengungen auf die Fasersubstruktur von Zink-Einkristallen

Zusammenfassung An Einkristallen von Zn mit Beimengungen von Cd oder Cu wurde experimentell die Abhä agigkeit der Größe des Durchmessers der Fasersubstruktur vom Gehalt der Beimengungen untersucht, die aus der Theorie von Rutter und Chalmers [1] hervorgeht. Es wird die Möglichkeit gezeigt, die Größe des Verteilungskoeffizientenk aus den erzielten Ergebnissen abzuschätzen.

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Прибор для измерения внутреннего затухан ия

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Temperature dependence of the spinS=1/2 fluctuation rate and the low-spin versus high-spin transition in native chloroperoxidase

We analyzed two preparations of native, low-spin ferric chloroperoxides as a function of temperature with the following results. (i) The spin lattice transition rateW(T) is relative slow, following a power lawW=0.035 (T/K)^4.98 (rad/s) for one of the samples. (ii) The quadrupole splitting is strongly temperature dependent, dropping from ¦E _Q¦ 2.94 mm/s at 100 K to 2 mm/s at 250 K. (iii) Starting at 190 K, the low-spin heme iron in frozen adqueous solution converts reversibly to a high-spin form, reaching 40% high-spin at 250 K. The two forms appear to be in thermal equilibrium, (iv) Optical data indicate that in a 70% glycerol glass, the conversion starts at lower temperature and reaches 50% highspin at 190 K.Supported in part by GM 49513 and GM 16406.     

Energy relaxation in disordered charge and spin density waves

We investigate collective effects in the strong pinning model of disordered charge and spin density waves (CDWs and SDWs) in connection with heat relaxation experiments. We discuss the classical and quantum limits that contribute to two distinct contribution to the specific heat (a Cv T-2 contribution and a Cv T contribution respectively), with two different types of disorder (strong pinning versus substitutional impurities). From the calculation of the two level system energy splitting distribution in the classical limit we find no slow relaxation in the commensurate case and a broad spectrum of relaxation times in the incommensurate case. In the commensurate case quantum effects restore a non vanishing energy relaxation, and generate stronger disorder effects in incommensurate systems. For substitutional disorder we obtain Friedel oscillations of bound states close to the Fermi energy. With negligible interchain couplings this explains the power-law specific heat Cv T observed in experiments on CDWs and SDWs combined to the power-law susceptibility (T)T-1+ observed in the CDW o-TaS3.     

The critical point indices of ferroelectric and ferromagnetic phase transitions

Magnetic transitions are described by the critical indices0,1/3,4/3 while some ferroelectric transitions appear to give0,R~1/2,1. It is pointed out that these two sets of values for the critical indices are allowed by the scaling laws and stability conditions near the phase transitions.The authors thank Prof. R. S. Krishnan for his encouragement and Mr. B. Viswanathan for some discussions. The financial assistance from DAE and CSIR is also acknowledged.     

Flow of low-density gases between parallel plates

The flow of inert gases, hydrogen, and deuterium was studied in a plane-parallel aperture 19 high formed by glass plates. A minimum volume flow rate is observed at a Knudsen number of 1. For Kn > 1, the volume flow rate increases without limit in the pressure range studied. The experimental results for the different gases differ greatly in the region of free molecular flow. Neon displays a behavior different from that of the other gases. The available theoretical results are compared with the experimental results.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 9, pp. 105–111, September, 1969.     

Unstable neutrinos can do it!

We present a cosmological scenario with unstable neutrinos which decay into a light neutrino and a relativistic boson. Theoretical and observational constraints severely narrow the values of mass and of lifetime of neutrinos. However, within this range, we can construct models with (i) = 1, (ii) age of the universe 13 billion years (b.y.) and (iii)h ₀ –0.5. The dynamical modeling shows that (a) the initial condensates of primordial _L are disrupted by the decay, lowering their masses to acceptable values ~10¹² M, (b) the relativistic boson contributes nearly 0.25 to, and (c) there emerge two prominent scales in dark matter distribution, one with a mass ~10¹² M distributed over 200 kpc around galaxies and another component with density 10^–27 g cm^–3 distributed over 1 Mpc. The model agrees with observations at all scales.This essay received an honorable mention from the Gravity Research Foundation for 1986-Ed.     

Solute Concentration Profiles for Discontinuous Dissolution in Al-22 at. % Zn Alloy

The discontinuous dissolution reaction has been analyzed in an Al-22 at. % Zn alloy. A simulation method based on the Ziba-Pawowski equation has been used to determine the solute concentration profiles expected to form behind the receding cell boundary for various initial values of the solute concentration in the lamella at the / interface as well as the solute concentration in the newly formed solid solution at the tip of the lamella. A criterion for the applicability of the Ziba-Pawowski model has been formulated. The simulated profiles are in a very good agreement with the experimental ones obtained by using a special procedure involving in situ observation and high spatial X-ray measurements in a transmission electron microscope.     

μ + SR studies of UM2Al3, M=Ni,Pd

Positive-muon spin rotation ( ⁺ SR) measurements have been carried out in the new heavy-fermion superconductors UM₂Al₃, M=Ni and Pd. In UNi₂Al₃ the observed ⁺ frequencies in zero applied field indicate commensurate antiferromagnetic (AF) ordering of U moments 0.1 _B /U atom. These moments coexist with superconductivity and have the highest values observed in an AF heavy-fermion superconductor. The absence of well-defined frequencies in zero-field ⁺ SR in the AF state of UPd₂Al₃ suggests symmetric ⁺ stopping sites. In this system ⁺ SR linewidths belowT _c yield a preliminary value of 8000 Å for the London penetration depth.     

Quantum supports and modal logic

LetA be a quasi-manual with finite operations. Associate to each E = {e ₁ ,..., e_n} A the set _E of modal formulas: (e ₁ ··· e_n), e_i (e ₁ ··· e_i–1 e_i+1 ··· e_n), i=1,..., n. Set _A = {_E|E A}. We show that supports ofA are in one-to-one correspondence with certain Kripke models of _A where the supports are given by {x |A x is true}.On leave from the Department of Mathematics, Pontificia Universidade Catolica, Rio de Janeiro, Brazil.     

Quasioptical superconducting hot electron bolometer for submillmeter waves

We report on a superconducting hot electron bolometer coupled to radiation via a broadband antenna. The bolometer, a structured NbN film, was patterned on a thin dielectric membrane between terminals of a gold slotline antenna. We investigated the response to submillimeter radiation (wave-lengths 0.1 mm to 0.7 mm) in the fundamental Gaussian mode. We found that the directivity of the antenna was constant within a factor of 2.5 through the whole experimental range. The noise equivalent power of the bolometer at 119 µm was 3 · 10^–13 W/Hz^1/2; a time constant of 160 ps was estimated.     

Unusual Behavior of Nanocrystalline Strontium Oxide Toward Hydrogen Sulfide

The thermodynamically favored reaction of solid strontium oxide with gaseous hydrogen sulfide is kinetically enhanced to a large degree by the use of higher surface area nanocrystalline SrO in the form of brush-like collections of metal oxide fibers. An unusual feature is that the reaction SrO + H₂S SrS + H₂O proceeds stoichiometrically at room temperature, but at higher temperatures the reaction efficiency goes down, apparently due to rapid temperature induced crystal growth of the nanocrystalline SrO. The samples studied vary in crystallite size from 20 to 27nm, while average particle size (nanocrystal aggregates) varies in the following order; aerogel prepared SrO (100nm) 相似文献   

A study of microcrack curing in the bulk of a metal using a model material

Specifics and peculiarities of the curing process of microcracks in the bulk of a metal are analyzed. In order to carry out the study, a model material was used, which represented a copper matrix with embedded iron particles. It is shown that heat treatment of microcracks in the bulk of the metal, according to the Lifshits-Slezov theory, leads to an increase in the volume of bigger irregularities at the expense of dissolving of smaller ones by vacancies. Furthermore, the total volume of the vacancy (/)_vol practically does not change.Kulyab State Pedagogical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 64–67, March, 1993.